People work out to stay in shape, but could your exercise routine cause you to lose your hearing?

Workouts help make fitness gains, but loud music may have you losing your hearing -- and fast. It literally made a first-time cycling student ill.

"I thought about leaving but I wanted to give it a try. But afterwards, I didn't feel well, I felt dizzy," said Mandev Khalsa of Santa Monica. "The noise level was awful."

Dr. John Goddard of the House Research Institute says the higher the decibel, or dB level, the shorter amount of time you ear can adapt.

"Loud noise exposure over prolonged periods of time or shorter periods of time , if it's excessive noise, can be damaging to the ear," said Goddard.

Not only is hearing loss painless, once lost, it won't come back. I attended six group exercise classes in Los Angeles and Orange counties to measure sound levels and got surprising results. Most registered in the 90 to 100 dB range -- think lawn mower or helicopter.

The worst I discovered was an indoor cycling studio at 106 decibels. Think about this: it's about 45 minutes of a sound of a jackhammer or chainsaw.

"You're there more than three minutes at that level, you're causing damage -- no question," said Goddard.